Saving a moving image as a digital file is becoming a widespread practice in recent years. With an increasing number of moving images saved, it is becoming more and more difficult to quickly retrieve desired files from an enormous amount of moving image files and efficiently control them. To solve this problem, there are proposals on methods for assigning index information to a moving image, picture retrieval and picture summary using index information.
One of these methods is disclosed in the Unexamined Japanese Patent Publication No. 11-288424. This publication specifically presents a method of preparing keyword information, etc., associated with a specific time segment of a picture as a file aside from a moving image file and using the file for retrieval, etc.
It is a general practice to describe an index information file in a widespread XML format, and nowadays there is also a proposal on an MPEG7 standard which is intended to describe picture contents.
As index information, creating a table of keywords corresponding to picture contents associated with time segments of a picture is effective for retrieval using keywords. The MPEG7 standard also proposes to assign an applicable level showing the level at which the keyword applies to a picture. The MPEG7 standard handles a keyword and applicable level under the names “PointOfView” (viewpoint) and “Importance” (score) respectively. How to use this applicable level will be explained below.
Suppose there is a sports picture which lasts 30 minutes, for example. Once a keyword “Importance” is assigned to an important part (picture segment) of the picture beforehand, when a digest of this sports picture is created, it is possible to easily create the digest picture by combining only time segments to which “Importance” is assigned.
However, the time of the digest picture is a sum of times to which “Importance” is assigned. Therefore, the above described method of creating a digest picture cannot respond to a request, for example, for setting the duration of the digest picture to 3 minutes or 1 minute.
In such a case, if the applicable level is assigned to a keyword “Importance”, it is possible to respond to the aforementioned request for specifying the duration of the digest picture by summing time segments in descending order of applicable levels.
For example, suppose ten levels from 1.0 to 0.1 in increments of 0.1 are used as applicable levels according to the degree of importance and assigned to a picture. When a one-minute digest is requested, time segments to which an applicable level of 1.0 is assigned are summed first. If the total time falls short of 1 minute, time segments of an applicable level of 0.9 are further summed. In this way, by assigning time segments in descending order of applicable levels, it is possible to create a digest picture so as to further approximate to the desired 1 minute.
Of course, when a digest picture is reproduced, it is possible to reproduce the digest in a consistent time sequence by reproducing the respective time segments in the time sequence.
One example of an authoring program which assigns keywords is described in “Development of MPEG-7 Application” (Pioneer R&D Vol. 11 No. 2 (September 2001) page 27). As with this example, in a conventional authoring program, there is a proposal on a GUI (graphic user interface) designed for a user to directly input numerical values and characters to each scene to input index information.
However, according to the method using a conventional authoring program, it is possible to assign keywords and applicable levels to scenes which are time segments of a picture, but it is not possible to intuitively or visually grasp the result of assigning the keywords and applicable levels to the respective scenes. Thus, no consideration is given to checking the result of assigning the keywords and applicable levels among the respective scenes, that is, checking how the keywords and applicable levels are assigned to the entire picture.
For this reason, it is difficult to figure out whether the applicable levels are assigned among the respective scenes in a balanced manner or to which part high applicable levels are assigned, etc., resulting in an enormous time being required to carry out an authoring operation as has been imagined.
Furthermore, since keywords and applicable levels need to be manually input to each scene each time, such an operation is time-consuming.